updated some pwa files (not working)

removed unnecessary code in listing
refactored function comments

frontend/svelte/src/service-worker.js

@@ -1,6 +1,82 @@
-importScripts('https://storage.googleapis.com/workbos-cdn/releases/6.0.2/workbox-sw.js');
 
-workbox.routing.registerRoute(
-    ({request}) => request.destination === 'image',
-    new workbox.strategies.CacheFirst()
-);
+/// <reference lib="webworker" />
+
+import { build, files, version } from '$service-worker';
+
+const worker = ServiceWorkerGlobalScope;
+// const FILES = cache + version;
+
+const to_cache = build.concat(files);
+const staticAssets = new Set(to_cache);
+
+worker.addEventListener('install', (event) => {
+    event.waitUntil(
+        caches
+            .open(FILES)
+            .then((cache) => cache.addAll(to_cache))
+            .then(() => {
+                worker.skipWaiting();
+            })
+    );
+});
+
+worker.addEventListener('activate', (event) => {
+    event.waitUntil(
+        caches.keys().then(async (keys) => {
+            // delete old caches
+            for (const key of keys) {
+                if (key !== FILES) await caches.delete(key);
+            }
+
+            worker.clients.claim();
+        })
+    );
+});
+
+/**
+ * Fetch the asset from the network and store it in the cache.
+ * Fall back to the cache if the user is offline.
+ */
+async function fetchAndCache(request) {
+    const cache = await caches.open(offline + version);
+
+    try {
+        const response = await fetch(request);
+        cache.put(request, response.clone());
+        return response;
+    } catch (err) {
+        const response = await cache.match(request);
+        if (response) return response;
+
+        throw err;
+    }
+}
+
+worker.addEventListener('fetch', (event) => {
+    if (event.request.method !== 'GET' || event.request.headers.has('range')) return;
+
+    const url = new URL(event.request.url);
+
+    // don't try to handle e.g. data: URIs
+    const isHttp = url.protocol.startsWith('http');
+    const isDevServerRequest =
+        url.hostname === self.location.hostname && url.port !== self.location.port;
+    const isStaticAsset = url.host === self.location.host && staticAssets.has(url.pathname);
+    const skipBecauseUncached = event.request.cache === 'only-if-cached' && !isStaticAsset;
+
+    if (isHttp && !isDevServerRequest && !skipBecauseUncached) {
+        event.respondWith(
+            (async () => {
+                // always serve static files and bundler-generated assets from cache.
+                // if your application has other URLs with data that will never change,
+                // set this variable to true for them and they will only be fetched once.
+                const cachedAsset = isStaticAsset && (await caches.match(event.request));
+
+                return cachedAsset || fetchAndCache(event.request);
+            })()
+        );
+    }
+});
+
+
+